The fractal nature of clouds in global storm-resolving models
Geophysical Research Letters American Geophysical Union 48:23 (2021) e2021GL095746
Abstract:Clouds in observations are fractals: they show self-similarity across scales ranging from one to 1000 km. This includes individual storms and large-scale cloud structures typical of organised convection. It is not known whether global storm-resolving models reproduce the observed fractal scaling laws for clouds and organised convection. We compute the fractal dimension of clouds using Himawari satellite data and compare this to global storm-resolving model simulations completed as part of the DYAMOND intercomparison project. We find cloud fields in these simulations are indeed fractal, and reproduce the observed fractal dimension to within 10%. We find the fractal dimension is sensitive to the choice of boundary layer parametrisation scheme used in each model simulation, and not to the convection parametrisation as might have been expected.
Scale‐aware space‐time stochastic parameterization of subgrid‐scale velocity enhancement of sea surface fluxes
Journal of Advances in Modeling Earth Systems American Geophysical Union (AGU) (2021)
OpenEnsemble 1.0: a boon for the research community
Geoscientific Model Development Discussions Copernicus Publications (2020)
Continuous structural parameterization: a proposed method for representing different model parameterizations within one structure demonstrated for atmospheric convection
Journal of Advances in Modeling Earth Systems American Geophysical Union 12:8 (2020) e2020MS002085
Abstract:Continuous structural parameterization (CSP) is a proposed method for approximating different numerical model parameterizations of the same process as functions of the same grid‐scale variables. This allows systematic comparison of parameterizations with each other and observations or resolved simulations of the same process. Using the example of two convection schemes running in the Met Office Unified Model (UM), we show that a CSP is able to capture concisely the broad behavior of the two schemes, and differences between the parameterizations and resolved convection simulated by a high resolution simulation. When the original convection schemes are replaced with their CSP emulators within the UM, basic features of the original model climate and some features of climate change are reproduced, demonstrating that CSP can capture much of the important behavior of the schemes. Our results open the possibility that future work will estimate uncertainty in model projections of climate change from estimates of uncertainty in simulation of the relevant physical processes.
The value of initialisation on decadal timescales: state dependent predictability in the CESM Decadal Prediction Large Ensemble
Journal of Climate American Meteorological Society 33:17 (2020) 7353-7370